According to wikipedia (almost as authorative as “my friend said he heard from someone in shul at a kiddush, that someone asked r’ chaim and he reportedly said”)….
Before wristwatches became popular in the 1920s, most watches were pocket watches, which often had covers and were carried in a pocket and attached to a watch chain or watch fob.[3] In the early 1900s, the wristwatch, originally called a Wristlet, was reserved for women and considered more of a passing fad than a serious timepiece. Men, who carried pocket watches, were quoted as saying they would “sooner wear a skirt as wear a wristwatch”.[4] This changed in World War I, when soldiers on the battlefield found pocket watches to be impractical and attached their watches to their wrist by a cupped leather strap. It is also believed that Girard-Perregaux equipped the German Imperial Navy with wristwatches in a similar fashion as early as the 1880s, to be used while synchronizing naval attacks and firing artillery.[4]